Week 2 - Musculo

Howdy,

All's well over in musculoland. I have yet to lay a hand on someone with Lx, Cx or come-on!, even a Thx problem. It's all knee related things for me baby. Anyway on the subject of knees, I don't know if any of you know much about autologous chondrocyte implantation? As it is not a really common proceedure I thought I would just share a bit of info about it. The actual Rx of the patient is relatively standard (and by this phase she has well progressed and we are looking at very functional positions for VMO, general LL strengthening, balance/proprioception). Anyway, the protocols that come with these patients are very long and relatively regimented and will be varied according to surgeon. It is a very long recovery process lasting up to 1.5yrs+. So here's a little info in brief (well, definitions of brief may vary....) for those interested:

➢ ACI - Generally indicated for the repair of symptomatic, cartilaginous defects of the femoral condyle (medial, lateral, trochlear) caused by acute or repetitive trauma or failed previous procedures.
➢ May also be performed on patellar and tibial defects


HOW?

• 2 step surgical procedure:
1. Arthroscopic biopsy (day surgery)
➢ A small piece of healthy articular cartilage is harvested.
➢ Over the next 4wks these chondrocytes are cultivated
2. Chondrocyte implantation (arthrotomy – open knee surgery)
➢ Cartilage defect is debrided down to subchondral bone
➢ The defect area is covered with a tissue-engineered bi-layer collagen membrane which is stitched in place and sealed with fibrin adhesive
➢ The cultivated chondrocyte suspension is then injected into this ‘chamber’
➢ Over time these cells will proliferate and regenerate their specific cartilage matrix thus repairing the defect.

PATIENT POPULATION?

• Predominantly for lesions >2cm
• Indicated as a secondary treatment after 1 or more failed alternative cartilage repair procedures
• Suitable if cause of defect is trauma (acute or repetitive) or osteochondritis (Inflammation of both bone and cartilage - several examples of this condition include: Kohler's disease, Osgood Schlatter's, Perthes' , Scheuermann's disease
• Age limits 15-55 (>55, the chondrocytes do not grow as well and at this age the articular cartilage is often too damaged for the procedure to be beneficial)
• Patients must be able and compliant with a lengthy rehabilitation
• Not suitable if the knee is unstable or malaligned. No varus or valgus deformities, intact cruciate ligaments required (these must be addressed first)
• Not for individuals with body weight > than 1.5 times the ideal body weight for height
• Not for any progressive inflammatory, osteoarthritis or rhematoid arthritides (they will simply continue to erode the area)

REHABILITATION

• As with all protocols………variation in rehab time/weight bearing status/exercises……..

• Broad timeline for maturation of the ACI graft:
➢ Proliferative stage: 0-6wks. Tissue fills the defect.
➢ Transition stage: Changes in tissue consistency. At the beginning of this stage it is a liquid. By 3-6months is has a gelatin-like consistency and is now well integrated to underlying bone and adjacent cartilage. At 6-9months this ‘neo-cartilage’ is like putty.
→ After 1 week like WATER
→ After 3 months like YOGURT
→ After 6 months like DOUGH
→ After 9 months like CHEESE
→ After 12 months like RUBBER
➢ Remodelling and maturation stage: lasts as long as 2 yrs as the matrix proteins continue to form cross-links and the collagen framework integrates into the subchondral bone

• The maturation process cannot be accelerated through rehab! Rehab is guided towards protecting the repaired surface to allow natural maturation while mobility, stability, strength and function are gradually progressed.